Explanations in Gesture, Diagram, and Word

Abstract

People are constantly explaining things to one another. Parents explain to children how to build a tower of blocks or why they need to go to bed. Friends explain to each other how to find their homes or why they were late. Teachers explain to students how nerve conduction happens or why the World War I began. In person, explanations, in common with most face-to-face communication, are typically multimodal. Not simply talk, explanations include gestures, props, and often diagrams (e.g. Engle, 1998). Each mode has relative advantages and disadvantages, and they work in concert, complementing and supplementing one another (e.g. Frequently, explanations are restricted to a single mode. Giving directions over the phone limits them to words. Providing instructions to operate a camera or assemble a piece of furniture to international consumers limits them to diagrams. Although gesture is often used alone for brief interchanges, like signalling to a partner a desire to leave a party, it is less likely to be solely used in complex explanations. Those who have got lost in a country whose language they don't know learn the power of gesture alone. Limiting communicators to a single mode requires completeness of that mode. This reveals the structure of explanations and the parallel ways each mode expresses that structure. Not all explanatory tasks readily lend themselves to words, diagrams, and gestures. Fortunately, two of the most common kinds of explanatory tasks do: navigation and construction. One of each was selected in order to investigate the structure and semantics of explanations. The navigation task was to communicate how to get from one place to another. The construction task was to communicate how to put together a piece of furniture, a TV cart. The data analysed here were gathered from several experiments differing somewhat in methods. In all cases, participants first learned or already knew the specifics of the task and then provided instructions so that another person could perform the task. In some experiments, participants were asked to provide verbal instructions,